Residency · Residency · General Surgery
Roux-en-Y Gastric Bypass and Sleeve Gastrectomy
Introduction
Roux-en-Y gastric bypass (RYGB) and laparoscopic sleeve gastrectomy (LSG) are the two most commonly performed bariatric operations worldwide. Together they account for over 95% of metabolic and bariatric procedures. The choice between these operations depends on patient characteristics, comorbidities, surgeon expertise, and shared decision-making. Both procedures produce significant, durable weight loss and comorbidity resolution through complementary restrictive, hormonal, and metabolic mechanisms. The general surgery resident must understand the operative technique, physiologic effects, expected outcomes, and postoperative management of both procedures.
Roux-en-Y Gastric Bypass
Mechanism of Action
The restrictive component derives from a small gastric pouch (15-30 mL) that limits meal size and produces early satiety. Hormonal changes result from bypass of the duodenum and proximal jejunum, which alters gut hormone profiles with increased GLP-1 and PYY from early delivery of nutrients to the distal ileum (the hindgut hypothesis) and decreased ghrelin (variable, related to exclusion of the gastric fundus). The malabsorptive component results from bypass of the duodenum and proximal jejunum, reducing absorption of iron, calcium, and some macronutrients, though the degree of malabsorption is modest in standard RYGB. Bile acid changes include increased circulating bile acids that activate FXR and TGR5 receptors, improving glucose metabolism and energy expenditure. Significant gut microbiome alterations after RYGB may also contribute to metabolic improvements.
Operative Technique
The patient is positioned supine in split-leg reverse Trendelenburg with 5-6 trocar placement and a liver retractor. Gastric pouch creation begins at the lesser curvature, 3-4 cm below the GEJ at the level of the crow's foot (the first branch of the nerve of Latarjet), with sequential firings of the linear stapler to create a small, tubular pouch oriented along the lesser curvature with a volume of approximately 15-30 mL, avoiding inclusion of excessive fundus which would create a noncompliant pouch. The pouch must be completely divided from the gastric remnant to prevent gastrogastric fistula.
Roux limb construction begins by identifying the ligament of Treitz and measuring 30-50 cm distally for the biliopancreatic limb. The jejunum is divided with a linear stapler, and the distal end becomes the Roux (alimentary) limb, which is typically 75-150 cm in length (100-150 cm for BMI above 50 or patients with diabetes to enhance the metabolic effect). The biliopancreatic limb measures 30-50 cm, and the common channel remains the longest segment.
The gastrojejunostomy is created by bringing the Roux limb antecolic-antegastric (preferred, as it reduces internal hernia risk) or retrocolic-retrogastric. A 1.0-1.5 cm anastomosis is created using a linear stapler with hand-sewn closure of the common enterotomy, a circular stapler (25 mm), or an entirely hand-sewn technique. The anastomosis is tested for leak with air insufflation, methylene blue, or endoscopy. The jejunojejunostomy is created as a side-to-side stapled anastomosis at the measured distance from the gastrojejunostomy (which determines the Roux limb length), and the common enterotomy is closed with a stapler or hand-sewn technique. Mesenteric defect closure is critical: the Petersen space defect (between the Roux limb mesentery and the transverse mesocolon) and the jejunojejunostomy mesenteric defect must be closed with running nonabsorbable suture to prevent internal hernia, as failure to close is the most common cause of small bowel obstruction after RYGB. Drain placement is optional and based on surgeon preference.
<image>Surgical illustration of the completed Roux-en-Y gastric bypass showing the small gastric pouch along the lesser curvature, the Roux (alimentary) limb with the gastrojejunostomy, the biliopancreatic limb, the jejunojejunostomy, and the common channel, with measurements labeled for standard limb lengths and arrows indicating the direction of food and biliopancreatic secretion flow</image>
Expected Outcomes
Excess weight loss is 60-80% at 1-2 years and 50-60% at 10 or more years, with total weight loss of 25-35% at 1-2 years. Type 2 diabetes remission (HbA1c below 6.5% off medications) occurs in 60-80% at 2 years, making RYGB the most effective bariatric operation for diabetes. Hypertension improves or resolves in 60-80%, dyslipidemia improves in 70-95%, and obstructive sleep apnea improves or resolves in 75-90%. RYGB is highly effective for GERD treatment and is considered the procedure of choice for patients with significant reflux.
Laparoscopic Sleeve Gastrectomy
Mechanism of Action
The restrictive component derives from removal of 75-80% of the stomach, creating a narrow tubular stomach with reduced capacity of 60-120 mL. The hormonal changes are significant: removal of the gastric fundus dramatically reduces ghrelin production (the major orexigenic hormone), while GLP-1 and PYY increase from accelerated gastric emptying and rapid nutrient delivery to the distal small bowel. There is no malabsorptive component, as the pylorus, duodenum, and entire small bowel remain intact with no altered intestinal continuity. Accelerated gastric emptying through the tubularized stomach with intact pylorus promotes rapid transit, contributing to early satiety and favorable hormonal changes.
Operative Technique
Patient positioning is the same as RYGB with 5 trocar placement and a liver retractor. Greater curvature devascularization begins by dividing the greater omentum and short gastric vessels 4-6 cm from the pylorus, proceeding cephalad to the angle of His. Care must be taken to fully mobilize the fundus from the left crus and diaphragm to avoid leaving a retained fundus, while preserving the gastroepiploic arcade and omentum attached to the greater curvature specimen.
Staple line creation begins with insertion of a 32-40 Fr calibration bougie transorally along the lesser curvature to guide staple line placement. The first staple firing begins 4-6 cm from the pylorus; starting too close narrows the antrum and increases stenosis risk, while starting too far leaves excess antral volume. Sequential firings of the linear stapler (green or gold/tan loads for the thicker antrum, blue loads for the thinner body and fundus) proceed along the bougie toward the angle of His, maintaining a consistent distance of 1-2 cm from the bougie to avoid narrowing or spiraling the sleeve. The last staple firing should be 1-2 cm from the GEJ to preserve the angle of His and reduce reflux. Staple line reinforcement options include oversewing with running absorbable suture, buttress material (SeriCuff, Seamguard, Peristrips), or no reinforcement; evidence is mixed, and reinforcement may reduce staple line bleeding but not leak rates. A leak test using upper endoscopy with air insufflation or methylene blue injection assesses staple line integrity. The resected stomach is removed through the 15 mm trocar site.
<image>Stepwise surgical illustration of the laparoscopic sleeve gastrectomy showing devascularization of the greater curvature, bougie placement along the lesser curvature, sequential staple firings from 4-6 cm proximal to the pylorus to the angle of His, and the final tubularized sleeve alongside the excised gastric specimen</image>
Expected Outcomes
Excess weight loss is 50-70% at 1-2 years and 40-60% at 5-10 years, with total weight loss of 20-30% at 1-2 years. Type 2 diabetes remission is 40-60% at 2 years, somewhat lower than RYGB, particularly for long-standing diabetes. Hypertension improves or resolves in 50-70%, and dyslipidemia improves in 60-85%. Regarding GERD, sleeve gastrectomy may worsen or cause de novo GERD in 20-35% of patients, though this is controversial as some studies show improvement; this is a significant consideration in patient selection.
RYGB Versus Sleeve Gastrectomy: Comparative Evidence
| Outcome | RYGB | Sleeve Gastrectomy |
|---|---|---|
| EWL at 5 years | ~68% | ~62% |
| T2DM remission | 60–80% | 40–60% |
| GERD | Significantly improved | May worsen (20–35% de novo) |
| Nutritional deficiencies | More common (Fe, Ca, B12) | Less common |
| Internal hernia risk | 2–5% lifetime | None |
| Reoperation for GERD/weight regain | Less common | More common (conversion to RYGB) |
SM-BOSS and SLEEVEPASS Trials (Randomized Controlled Trials)
Weight loss is similar at 5 years, though RYGB may produce slightly greater excess weight loss (68% versus 62%). RYGB is superior to sleeve for diabetes remission, particularly for long-standing or insulin-dependent diabetes. RYGB significantly reduces GERD while sleeve may worsen it. Overall complication rates are comparable, though the types differ: internal hernia and marginal ulcer occur after RYGB, while staple line leak and GERD occur after sleeve. Nutritional deficiencies are more common after RYGB (iron, calcium, B12, fat-soluble vitamins), though sleeve patients still require supplementation. Sleeve patients are more likely to require conversion to RYGB for weight regain or GERD.
Procedure Selection Considerations
RYGB is favored for patients with significant GERD or Barrett's esophagus, type 2 diabetes (especially long-standing or insulin-dependent), BMI above 50 (super obesity), and previous gastric banding. Sleeve gastrectomy is favored for younger patients, those needing future endoscopic access to the stomach or biliary system, patients with inflammatory bowel disease, high-risk surgical candidates (shorter operative time), and when it aligns with patient preference for simpler anatomy. Shared decision-making is essential, as both procedures are effective, and informed discussion should cover expected outcomes, risks, lifestyle changes, and long-term follow-up requirements.
Postoperative Management
Dietary Progression
Phase 1 (days 1-14) consists of clear liquids advancing to full liquids, with protein shakes beginning immediately. Phase 2 (weeks 2-4) introduces pureed foods with a focus on protein-rich options. Phase 3 (weeks 4-6) advances to soft foods with gradual texture progression. Phase 4 (week 6 onward) allows regular solid foods with emphasis on protein first (minimum 60-80 g/day), avoiding sugar, limiting carbohydrates, and eating small frequent meals. Fluid intake should be at least 64 oz per day, and patients should avoid drinking with meals (waiting 30 minutes before and after eating). Lifelong dietary guidelines include avoiding carbonated beverages, concentrated sugars, and high-fat foods, chewing thoroughly, and stopping eating when full.
Vitamin and Mineral Supplementation (Lifelong)
A multivitamin with minerals is taken twice daily (containing iron, folic acid, and thiamine). Calcium citrate is supplemented at 1200-1500 mg/day in divided doses (the citrate form is better absorbed without stomach acid). Vitamin D is supplemented at 3000-6000 IU/day with monitoring of 25-OH vitamin D levels. Vitamin B12 at 1000 mcg/day sublingual or as a monthly intramuscular injection is especially important after RYGB due to loss of intrinsic factor production. Iron at 45-60 mg elemental iron daily is recommended, with menstruating women potentially needing more; it should be taken with vitamin C and separated from calcium. Thiamine (B1) should be supplemented in patients with protracted vomiting to prevent Wernicke encephalopathy. Annual lab monitoring includes CBC, CMP, iron studies, B12, folate, vitamin D, PTH, vitamin A, zinc, copper, and thiamine.
Follow-Up Schedule
During the first year, follow-up visits are at 2 weeks, 6 weeks, 3 months, 6 months, and 12 months. After the first year, annual follow-up is recommended lifelong with lab monitoring, nutritional counseling, and support group participation. Weight regain assessment should evaluate dietary compliance, psychological factors, and anatomic issues (pouch dilation, GJ dilation), with consideration of endoscopic or surgical revision.
Key Clinical Pearls
Roux-en-Y gastric bypass is the superior operation for patients with GERD, Barrett's esophagus, or type 2 diabetes requiring maximum metabolic effect. Sleeve gastrectomy may worsen or cause de novo GERD and should be avoided in patients with significant preexisting reflux. Closure of mesenteric defects during RYGB is essential to prevent potentially life-threatening internal hernias. Lifelong vitamin and mineral supplementation is mandatory after both procedures, and non-compliance leads to preventable deficiencies including anemia, metabolic bone disease, and neurological complications. Both procedures produce comparable long-term weight loss, and procedure selection should be individualized based on patient comorbidities, anatomy, and informed preference.
References
- Peterli R, Wolnerhanssen BK, Peters T, et al. Effect of laparoscopic sleeve gastrectomy vs laparoscopic Roux-en-Y gastric bypass on weight loss at 5 years among patients with BMI 35-45 (SM-BOSS). JAMA. 2018;319(3):241-254.
- Salminen P, Helmio M, Ovaska J, et al. Effect of laparoscopic sleeve gastrectomy vs laparoscopic Roux-en-Y gastric bypass on weight loss at 5 years (SLEEVEPASS). JAMA. 2018;319(3):241-254.
- Mechanick JI, Apovian C, Brethauer S, et al. Clinical practice guidelines for the perioperative nutrition, metabolic, and nonsurgical support of patients undergoing bariatric procedures (AACE/TOS/ASMBS). Surg Obes Relat Dis. 2020;16(2):175-247.
- Aminian A, Zajichek A, Arterburn DE, et al. Association of metabolic surgery with major adverse cardiovascular outcomes in patients with type 2 diabetes and obesity. JAMA. 2019;322(13):1271-1282.
